FIGS. 1-3 show currently popular forms of automobile sunroof air, or wind, deflectors. In the version shown in FIGS. 1 and 2, the deflector has a visor element 20 vacuum formed from a single sheet of acrylic. The visor has: a gently sloping, generally planar top portion 22 that extends over a front part of the sunroof opening 12 on the automobile's roof 10; a front portion or edge 24 for location on the roof immediately in front of the opening, and which extends longitudinally slightly beyond the width of the opening 12; and, upstanding side portions 26 extending transversely to the rear of the front portion 24 closing each end of the visor. The top, front and side portions all meet at an elbow or corner 28 of the visor. The visor is retained on the roof by a screw 30 and bracket 32 arrangement near each corner 28. The bracket has a hook 33 at one end for engaging beneath a flange 14 along the perimeter of the opening, and the screw 30 extends through a hole 21 near the corner of the visor to engage the bracket and thereby clamp the visor to the roof. A gasket 34 is typically adhered along the visor's perimeter with the aim of preventing damage to the roof's painted exterior surface.
In an alternate arrangement shown in FIG. 3 a two-sided tape 36 may be used along the perimeter of the visor for mounting to the roof, either with or without the previously described screw and bracket arrangement.
The above prior art arrangements suffer from several disadvantages:    the adhesives for the gaskets may react with the acrylic deflectors and result in “crazing” and/or discoloration of the visor;    plasticizers in the flexible gaskets also adversely chemically attack the acrylic material of the deflectors;    the exposed fasteners result is visual clutter and pose corrosion problems;    the corners of the visor are put under tension by the pull of the brackets to ensure that the gasket is compressed on the roof, but this causes stress concentrations and possible cracks at the holes, and predisposes the visor to material fatigue;    temperature fluctuations cause material stresses which result in buckling and warping of the visor;    the vacuum forming process for the visor is quite complicated, expensive and delicate due to the difficulty in forming the corners 28, and imparts undue localized stresses at such corners; and,    the prior art products are labour intensive to manufacture (e.g. the edge finishing) and to install because the nuts are difficult to reach and the location of the screws lead to a large percentage of discarded product when visors are scratched during screw installation.
What is therefore desired is a novel air deflector arrangement which overcomes the limitations and disadvantages of the existing products.